Genus - Notonecta

Taxonomic Hierarchy for Freshwater Invertebrate Collection


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3 results for "Notonecta"

Notonecta kirbyi

Freshwater Invertebrate Collection

SeasonalityBivoltine, adults over-winter laying eggs in spring and summer. Poorly documented life history. IdentificationWithin Alberta there are two other species which may be confused with Notonecta kirbyi: N. borealis and N. undulata. Of these, N. borealis occurs only in the boreal region and N. undulata is found across all of North America (Brooks and Kelton 1967, Hungerford 1917). As an adult N. kirbyi is the largest of the Alberta Notonectids (12-15 mm). Notonecta borealis may be differentiated from N. kirbyi by its white head, scutellum and hemelytra. As there is a great deal of variation in N. undulata it may be difficult to tell it apart from N. kirbyi by colouration. The head to propleuron of N. kirbyi is greenish yellow and the scutellum is always black, whereas N. undulata may be variable colours including yellow, green and has a black scutellum. Brooks and Kelton (1967) use morphological differences in eye colouration and the space between the eyes at the vertex of the head to distinguish very similar-looking individuals. Notonecta kirbyi's eyes are red, and the space between them at the vertex is about one half the distance of the distance between the perimeter of the eyes at the frons. Notonecta undulata's eyes are black. The distance between its eyes at the vertex is less than one half of the total distance between the perimeters of the eyes at the frons. Keel hairiness always reliably tells the difference between the two species under a dissecting microscope. Notonecta kirbyi has a bare keel on the fourth abdominal sternite that is hairy on both sides (Brooks and Kelton 1967). Notonecta undulata has a line of hair on the fourth abdominal sclerite keel (Brooks and Kelton 1967). The most distinguishing feature of N. kirbyi are its large, cloudy bands stretching across the leathery section of the hemelytra (from the inner edge of the clavus to the outer costal margin). Notonecta kirbyi is synonymous with N. insulata (Uhler), N. insulata var. impressa, N. (Paranecta) kirbyi (Henry and Froeshner 1988).

Notonecta sp.

Freshwater Invertebrate Collection

Notonecta undulata

Freshwater Invertebrate Collection

SeasonalityTwo broods per year, mid-May and July. Those hibernating can live through next August. IdentificationNotonecta undulata (10-12 mm) is the smallest, most elegant of the adult Albertan notonectids (10-12 mm), and is pale rather than all white (Brooks and Kelton 1967). The black scutellum, occasionally with light spots at the apex, and pale hemelytra blend in with the sky when seen from below. The ventral surface is dark, blending in with the sediments when seen from above. Using a microscope or powerful hand-lens, one can see its hairy central keel on the underside of the fourth abdominal sclerite. This differentiates N. undulata from the two other Albertan notonectids, N. kirbyi and N. borealis (Brooks and Kelton 1967). In the boreal region only one species, N. borealis may be confused with N. undulata. Notonecta borealis is a larger (12-14 mm) and predominantly white species, not pale yellow or light green. Other than its smaller size and thinness, brown anterior femurs differentiate N. undulata from N. borealis, which has brown coxae in addition to femurs brown on the ventral-side (Brooks and Kelton 1967). South of the Edmonton region in the Alberta prairie zones, N. kirbyi can be differentiated by size alone. It is the largest species in Canada (12-15 mm). The hemelytra of N. kirbyi are also distinctive: hemelytra membranes are black at the anterior portion but fades clear towards the tip and there are broad, cloud-like bars which stretch across the clavus to the cuneus. Alternatively, N. undulata wing membranes are pale with a large, irregular spot on the median line (Brooks and Kelton 1967). The only Albertan species of Anisopinae, Buenoa confusa, can be diffentiated from all Notonectinae by its three segmented beak and antennae, smaller size (5-8mm) and shininess (Hungerford 1917 a, b, Brooks and Kelton 1967). Notonecta undulata is synonymous with N. punctata Say, N. (Paranecta) undulata, and N. undulata var. charon Kirkaldy (Henry and Froeshner 1988).

Taxonomic Hierarchy for Freshwater Invertebrate Collection